len: add disclaimer about not-len-first assetions

README.md

@@ -651,6 +651,12 @@ assert.Len(t, arr, len(expArr))
 **Enabled by default**: true. <br>
 **Reason**: More appropriate `testify` API with clearer failure message.
 
+> [!CAUTION]
+> The checker ignores assertions in which length checking is not a priority, e.g.
+> ```go
+> assert.Equal(t, len(arr), value)
+> ```
+
 ---
 
 ### negative-positive

internal/checkers/len.go

@@ -33,6 +33,10 @@ import (
 //	assert.Len(t, arr, 42)
 //	assert.Len(t, arr, value)
 //	assert.Len(t, arr, len(expArr))
+//
+// The checker ignores assertions in which length checking is not a priority, e.g
+//
+//	assert.Equal(t, len(arr), value)
 type Len struct{}
 
 // NewLen constructs Len checker.